Problem: $ { \left[\begin{array}{rr}{4} & {-2} \\ {-1} & {4}\end{array}\right]+\left[\begin{array}{rr}{1} & {0} \\ {0} & {1}\end{array}\right] = {?} } $
Explanation: To find the sum of two matrices, add the corresponding items between each matrix. ${\left[\begin{array}{rr}{4}+{1} & {-2}+{0} \\ {-1}+{0} & {4}+{1}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{5} & {-2} \\ {-1} & {5}\end{array}\right]}$